<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        .atguigu1 {
            font-size: 40px;
        }
        .atguigu2 {
            font-size: 30px;
        }
        .atguigu3 {
            font-size: 20px;
        }
        .atguigu4 {
            font-size: 20px;
        }
    </style>
</head>
<body>

    <div class="atguigu1">尚硅谷1</div>
    <div class="atguigu2">尚硅谷2</div>
    <div class="atguigu3">尚硅谷3</div>
    <div class="atguigu4">尚硅谷4</div>
    
</body>
</html>